let server = require("express")();
let mysql = require("mysql");
//端口
let port = 8080;
// 规划链接
let sql = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '123456',
    database: 'user'
});

// 尝试链接
sql.connect();


//解决跨域
server.all("*", function(req, res, next) {
    //设置允许跨域的域名，*代表允许任意域名跨域
    res.header("Access-Control-Allow-Origin", "*");
    //允许的header类型
    res.header("Access-Control-Allow-Headers", "content-type");
    //跨域允许的请求方式 
    res.header("Access-Control-Allow-Methods", "DELETE,PUT,POST,GET,OPTIONS");
    if (req.method.toLowerCase() == 'options')
        res.send(200); //让options尝试请求快速结束
    else
        next();
})

//去登陆按钮
server.get(`/goLogin`, function(request, response) {

    let username = request.query.username;
    let password = request.query.password;

    sql.query(`SELECT * FROM login WHERE username="${username}"`, function(error, data) {
        if (error) {
            console.log(error);
            response.end("error");
            return;

        }

        if (data.length === 0) {
            console.log("该用户不存在！");
            response.end("none");
            return;
        }
        if (data[0].password === password) {
            console.log("登录成功");
            response.end("success")
        } else {
            console.log("用户名或密码输入错误");
            response.end("error")
        }

    })
})

//去注册按钮
server.get(`/goRegister`, function(request, response) {
    // response.end("success")
    let username = request.query.username;
    let password = request.query.password;

    sql.query(`SELECT * FROM login WHERE username="${username}"`, function(error, data) {
        if (error) {
            console.log(error);
            response.end("error");
            return;
        }
        //判断数据库中是否有前端传来的用户名，不能重复注册
        if (data.length === 0) {
            sql.query(`INSERT INTO login (username,password) VALUES ("${username}","${password}")`, function(error, data) {
                if (error) {
                    console.log(error);
                    response.end("error");
                    return;
                }
                response.end("success");
                console.log("该条新数据添加成功！");

            })
        } else {
            console.log("该条数据已被注册！");
            response.end("exist");
        }
    })
})



server.listen(port)
console.log(`server is running at ${port}`);